0762abs

Source characterization and identification as a means of assessing the type of bonding in the soil and its subsequent impact on bioavailability

P. Mulvey and C. McKay

Abstract

Polycyclic aromatic hydrocarbons (PAH), which are nearly ubiquitous, result from a large number of processes. Knowing the source of PAHs in fill and soil assists understanding of bioavailability and facilitates remediation. For example, PAHs from boiler ash and coke are not readily available, while PAHs from soil impregnated with gasworks waste are very bioavailable. Using the understanding of their chemistry, the relationships between PAHs and other hydrocarbons, and the proportions of individual PAHs; the source of the PAHs in fill can be readily identified. Two statistical methods are used to delineate PAH source by ranking the degree of fit with known sources, are outlined. Understanding that more volatile, more biodegradable and more leachable compounds are lost at a greater rate, adjustments can be made for aging, enabling more accurate source delineation. In this paper, using the two methods as an example of the procedure, we compare several unknown samples with known reference samples from waste oil, steel works coke ovens and manufactured gasworks waste, as well as creosote from timber preservation, processed PAHs, ash from black coal, ash from brown coal and diesel. This paper also poses two questions: should furnace-fired PAHs be removed to landfills (remediated) when fireplace ash is ubiquitous and so much of our urban soil is currently “carcinogenic”? When different waste streams from gasworks or other PAH generating industries have different remediation criteria, should PAH sources and their inherent bioavailability be considered in deriving health risk assessment guidelines?